When a guy asks if a lady wants to "party", at least in this neck of the woods (Ottawa), it almost always mean partake in drug use. In my experience it means hard drugs. If your definition of "party" is something else, I suggest you clarify what you mean.
Dangerous? Because first of all, it's illegal and someone can be unpredictable when they are indulging in substances, especially chemicals.
It's been my experience that when you bring drugs into the picture (this business), it is always a recipe for disaster, not just from a health and safety point of view, but ultimately a legal point of view.
Besides most legitimate providers do not fit the typical profile of "party" girl. The smart ones are who may are certainly not going to indulge with clients and if they do, their reps are sure to follow.
Not a wise question to ask on a board like this. Because then your rep will be questioned. My two cents.